In b2b a certain amount of cold pitching is certainly expected and while sending individual emails to a few select companies yourself with a message will yield a very small response rate, no one who you have a direct connection too will really balk at you messaging them. It's individual outreach and it happens online, in snail mail and in person every day.
When you start talking about automation and harvesting emails [which is what scraping Craigslist is] you've crossed well over into the "real" spam world. Sure your volumes are lower but it's still bulk messaging. That's your line. People are not going to Craigslist to be contacted by you and they explicit say this on their listings [almost everyone checks the "do not contact me with commercial services" button"]. I'm still not a lawyer but start mass messaging those people through their network and you'll lucky if all that happens is Craigslist bans your domain --you've got a contractual agreement with Craigslist to use their site, CAN SPAM is only part of the equation:
You agree not to post, email, or otherwise make available Content:
l) that constitutes or contains any form of advertising or solicitation if:
posted in areas of the craigslist sites which are not designated for such
purposes; or emailed to craigslist users who have not indicated in writing that
it is ok to contact them about other services, products or commercial interests.
Additionally, you agree not to:
r) contact anyone who has asked not to be contacted, or make unsolicited
contact with anyone for any commercial purpose;
u) use automated means, including spiders, robots, crawlers, data mining
tools, or the like to download data from the Service - unless expressly
permitted by craigslist;
- NO SPAM POLICY
You understand and agree that sending unsolicited email advertisements to
craigslist email addresses or through craigslist computer systems, which is
expressly prohibited by these Terms, will use or cause to be used servers
located in California. Any unauthorized use of craigslist computer systems
is a violation of these Terms and certain federal and state laws, including
without limitation the Computer Fraud and Abuse Act (18 U.S.C. Ã‚Â§ 1030 et
seq.), Section 502 of the California Penal Code and Section 17538.45 of the
California Business and Professions Code. Such violations may subject the
sender and his or her agents to civil and criminal penalties.
So by all means, talk to businesses you know and have a connection with but know that line. Ignorance is not a defense in the eyes of the law.